Telephone system.



PATENTED 0013-30; 1906.

w. w. DEAN. TELEPHONE SYSTEM. APPLICATION IILED DEO. 29, 1902.

2 SHEETS-QEIIBT'L RRIS PETERS 60., Iluungumu, :4 c.

w. w. DEAN.

TELEPHONE SYSTEM.

urmqyngn FILED D30. 2a. 1902.

2 SHEETS-SHEET 2 PATENTED OCT. 30, 1906.

f Al UNIT D s'r TEs WILLIAM W. DEAN, GIT CHICAGO. ILLINOIS,

PATENT OFFICE.

ASSIGNOR TO KELLOGG CORPORATION or ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Oct. 30, 1906.

Applioationfiled December 29, 1902. Serial No. 137,001.

To all whom it may concern:

Be it known that I, WILLIAM W. DEAN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented new and useful Improvements in Telephone Systems, of which the following is a specification. v

My invention relates to means for more perfectly balancing the talking-circuit when two lines are connected together for conversation. In certain classes of lines the cut-off relays .or other auxiliary devices are connected with one side of the lines, whereby when they are connected for conversation by the usual cord-circuit the metallic talkingcircuit is thrown out of balance. My invention is designed to balance such lines during conversation, which I accomplish by transposing the connections of the strands of the cord-circuit-that is, by connecting the tipcontact ofone plug with the sleeve-contact of the other cooperating plug. When the lines are connected together by this cord-circuit, the said cutoff relays orother auxiliary devices are connected with the opposite sides of the metallic talking-circuit and the balanced lineresults, thereby improving trans mission and avoiding cross-talk and other injurious or deleterious effects.

- A further objectis to provide a system in which the testing to determine the idle or busy condition of the wanted telephone-line is carried out in a simple and convenient manner.

My invention is illustrated in the accompanying drawings, in which the same reference characters are used to designate like parts throughout, and in which- 1 Figure 1 is a diagram ofa system embodying' my improvements. Fi g. 2 is a simplified diagram of the talking-circuit, and Fig. 3 is a diagram of a different system including my improvements.

In Fig. 1, L and L indicate subscribers lines extending in two limbs 2 and 3 from their respective substations to the central ofiice C. At the substation A a bell 4 and a condenser 5 are located in a preferably permanent bridge ofthe line conductors, while a transmitter 6 and receiver 7 are placed in a bridge that is normally open at the switchhook 8. At the central office the line conductor 2 is normally grounded through a branch 9, while the conductor 3 is normally connected with a conductor 10, including the winding of the line-relay R, and is then joined by the common lead 11 with the live pole of a preferably common battery B. The line-relay R controls, through its normally open contacts. the circuit of the line-signal S, which is preferably in the form of a small incandescent lamp. Each line is further provided with an answering-jack J and with any suitable number of multiple jacks, such as J 2 and J The tip and sleeve contacts of these jacks are connected with the forward contacts of the springs of the cutoff relay R of the line, the winding of which is grounded from the sleeve conductor of the said jacks. The line L is of the same type as the line L except that the subscribers bells are grounded from the opposite line conductors.

At the central ofiice each operator is provided with a plurality of cord-circuits each of the kind illustrated in the drawings and which is provided with an answering-plug P and a calling-plug P having tip and sleeve contacts adapted to register with the corresponding contacts of the spring-jacks or connection-terminals of the telephone-lines. The tip of the plug P is joined by the flexible strand t, condenser c, and the flexible strand 5 with the sleeve of the plug P while the sleeve of plug P is connected by strand 8, condenser 0 and tip-strand t with the tip of plug P The connections between thecontact-surfaces of the plugs, are therefore trans-- posed, cross connected, or F diagonally joined, as it is sometimes called. The battery B is, together with supervisory relays 1' and r bridged across the answering end of the cord-circuit, the former relay'controlling, through its normally closed contacts and the latter through its normally open contacts, the circuit of the supervisory lamp S ,which is preferably lighted from the battery B. The battery B together with the supervisory relays r and 1-, are likewise bridged across the calling end of the cord-circuit and similarly control the circuit of the supervi- 'by the depression of sory signal S associated with the callingplug P The branch containing the supervisory relay 1" is severed at spring 12 of sleeve supervisory relay 7* and is normally connected thereby with the conductor 13, leading to the high-resistance and high-impedance test-relay 1", the opposite pole of which is grounded. This relay serves when energized to ground a portion of the operators transmitter-circuit to thereby cause inductively a click in her receiver. transmitter 14 is connected in a conductor 15, joined to the common wire 11 connected With the live pole of the battery B said conductor 15 including the retardation-coil 16. The primary winding of the operators induction-coil 17, together with a condenser 0 are connected in shunt of the transmitter 14.

he operators receiver, a secondary of her induction-coil 17, and a suitable condenser are adapted to be connected across the calling end of the cord-circuit by means of the springs 18 of any suitable listening-key. A ringing-generator 19 is arranged to deliver alternating current to the tip side of the line springs 20 of any suit able ringing-key, the sleeve side being at the same time connected, through a resistance 21 in wire 22, through an auxiliary path, with the live pole of said battery B. By the operation of springs 23 of the ringing-key pulsating current from the generator 19, preferably of negative polarity, is directed over the sleeve conductor of the line, while a tip conductor is simultaneously grounded.

In the operation of the system the sub scriber at station A takes up his receiver, and thereby closes a path for current from the battery B, located at the central ofiice, over the conductor 11, through line-relay R, conductor 10, sleeve-limb 3 of the telephoneline, through the substation instruments, and back over limb 2 of the telephone-line to the central office, and thence through branch 9 to ground. The current in this path energizes the line-relay R, causing it to close the circuit of the line-signal S, which is lighted to indicate the subscribers call. Upon observing the signal the operator inserts the answering-plug P in the answering-jack of the line and connects her head-telephone with the cord-circuit to receive the order from the subscriber. The insertion of the plug P completes a local circuit for the cut-off relay R over the sleeve-strand s of the answeringcord and the sleeve conductor of the jacksv This relay is therefore energized to disconnect the tip-line conductor from the ground and the sleeve-line conductor from the relay R, while the switchboard conductors are 0011- nected with the external-line circuit for conversation. The sleeve supervisory relay r is likewise energized to close a local circuit of the supervisory lamp S which, however, is

The operatws prevented from operation at this time by reason of the actuation of relay 7* by current flowing over the metallic telephone-line.

Upon receiving the order for the connec tion the operator tests the condition of the wanted line in the usual manner by touching the tip of the plug P to the test-ring of the line. If the line is idle, the test-rings are grounded through the cut-oif relay, and no flow of current over the testing-circuit results, since the tip of the plug is likewise con.- nected, through the said test-relay, with ground. If the line is connected for conversation, however, the test-rings are raised to the potential of the battery B or B by the sleeve conductor of the inserted cord. The application of the tip of the plug therefore results in a flow of current over the tip-strand t through the branch connected with the spring 12 of relay T and, thence over conductor 13 to the test-relay 1" and to ground. The flow of current over this path energizes the said test-relay, causing it to complete a circuit through the primary winding of the operators set, whereby a click is inductively caused in the operators receiver. Owing to the high resistance and high impedance of the test-relay, a change of current upon the tested lines is neither great 1101 sudden, so that the subscribers receivers are not harmfully affected.

Assuming that the line is found idle, the calling-plug of the cord-circuit is inserted and the ringing-springs 20 or 23 actuated to call the wanted subscriber. The depression of springs 20 serves to call subscriber E, whose bell is connected with the tip side of the line, the cut-off relay R of the said line being maintained actuated by current over conductors 1.1 and 22 during ringing, while the operation of the ringing-springs 23 serves to call subscriber D, since his bell is grounded from the other side of the line, the cut-oil relay now being energized by the pulsating current from the ringing-generator and which is preferably of the same polarity as that im pressed upon the line by the battery 13.

After calling the subscriber and before his response the sleeve supervisory relay r is actuated to close the circuit of the supervisory signal S and to also close, through its spring 12, a branch from the tip conductor 15 of the tip supervisory relay 1. The supervisory lamp is therefore lighted to indicate the fact that the subscriber has not yet responded. As soon as the subscriber replies current from the battery B flows over the metallic circuit of the wanted line, thus operating the tip supervisory relay r and extinguishing supervisory lamp S The subscribers are now in communication, and the batteries B and B are furnishing current to the respective lines for transmission purposes and for the operation of the various supervisory and other relays associated therewith. By the transposition of the cord-circuit conductors the cut-off relays R of the two lines are now legged to round from the opposite sides of the metalic talkin -circuit. This condition is more clearly in icated in Fig. 2, in which the talking-circuit is indicated by the rectangular outline, from which it is seen that the cut-0E relays are legged to ground from the opposite sides of the metallic circuit. Likewise the central batteries are rounded upon the opposite sides, and a fulIy-balanced circuit t roughout is thus provided.

It will be understood that the substation apparatus may be of any desired type, that shown being merely typical of any suitable common battery outfit, that the several grounds mentioned at the central ofiice may be one and the same, or the common ofiice return, and that various other modifications may be made throughout without departing from the spirit or scope of my invention. Different types of line-circuits may be employedas, for example, those in which the switchboard-sections are permanently connected with the external line-circuits-since, broadly considered, my invention is not limited to this feature.

In Fig. 3 I have shown the diagonally-connected cord-circuit as used with the different type of line-circuit. low-resistance cut-off relay R and ahigh-resistance line-relay R are connected in series with the central source of current, the highresistance line-relay only responding to ourrent in the line when the subscriber takes up his receiver and calls the central oflice, since the cut-off relay does not receive suflicient current to actuate the same. When a connection is established with a line,however, the said cut-off relay is included in the local circuit over the sleeve-strand of the cord and the sleeve conductor of the permanently-connected jacks, with the result that a sufficient flow of current takes place through the said relay to actuate the same to thereby render inoperative a signal of the line. This action takes place whether or not the line-circuit is open at the substation. During conversation the said cut-off relays are connected with the opposite sides of the metallic talking-circuit the same as in Fig. 2, with the result that the talking-circuit is balanced throughout. This arrangement is accomplished by the connection of the tip-contact of one plug with the sleeve-contact of the opposite plug. The other apparatus shown in connection with Fig. 3 is well understood and in view of the specific description of Fig.

. 1 is not particularly described herein.

I claim-- 1. In a telephone system, the combination with telephone-lines, of a common source of In this line-circuit a current and signaling devices for the line-circuits, cut-off relays connected between the same sides of the lines and-one pole of said source and adapted when operated to render said signals inoperative, a diagonally-connected cord-circuitto establish connections with the lines for conversation and arranged to close a balanced circuit for voice-currents during conversation, substantially as described.

2. In a tele hone system, the combination of telephoneines having signaling devices, of cut-ofi relays connected to a common point from one sideof the circuits, a cord-circuit to establish connections with the lines for conversation, said cord-circuit having the conductors cross-connected, and means for feeding current out over the conductors of said circuit to actuate the cut-off relays, said arrangement of cord-circuit conductors placing the cut-off relays on op osite sides of the metallic talking-circuit, substantially as described.

3. In a telephone system, the combination with telephone-lines having cut-ofi relays legged to ground from one side of the lines, of a diagonally-connected cord-circuit to establish connections between lines for conversation, said cord-circuit having a condenser in each conductor, and current oflike polarity applied to the corresponding conductors included between the said condensers and each plug, substantially as described.

4. In a telephone system, the combination of telephone-lines having cutoff relays legged to a common-conductor from one of the sides of the lines, a diagonally-connected cord-circuit for establishing connections with the lines for conversation, said cordcircuit being divided by condensers into two independent battery-circuits, said portions of the cord-circuit being provided with supervisory apparatus so that the supervision of each line connectionis independent of the other, substantially as described.

5. In a telephone system, the combination with telephone-lines having their cut-oft relays legged to round from one of the sides of the lines, a iagonally-connected cord-circuit for establishing connections with the lines forconversation, said cord-circuit being divided into two portions, each of which forms a separate circuit for the current actuating the signaling devices in that portion of the talking-circuit, substantially as described.

6'. In a telephone system, the combination with telephone-lines having inductive devices adapted to form a portion of a local circuit legged from one of the sides of the lines to a common point, a diagonally-connected cord-circuit terminating in plugs provided with tip and sleeve contacts adapted to regis- Signed by me at Chica go, county of Cook,

State of Illinois, this 17th day of December,

WILLIAM W. DEAN.

Witnesse ROBERT LEWIS AMEs,

GAZELLE BEDER. 

